U.S. patent number 5,264,272 [Application Number 07/984,471] was granted by the patent office on 1993-11-23 for resistor paste and ceramic substrate.
This patent grant is currently assigned to Asahi Glass Company Ltd.. Invention is credited to Yoshiyuki Nishihara, Ryuichi Tanabe.
United States Patent |
5,264,272 |
Tanabe , et al. |
November 23, 1993 |
Resistor paste and ceramic substrate
Abstract
A resistor paste comprising an inorganic component which
consists essentially of from 20 to 70 wt % of glass powder and from
30 to 80 wt % of a powder selected from the group consisting of
SnO.sub.2 power, Sb-doped SnO.sub.2 powder and a mixture thereof,
wherein the glass powder consists essentially of from 12 to 50 wt %
of SiO.sub.2, from 0 to 20 wt % of Al.sub.2 O.sub.3, from 0 to 40
wt % of MgO, from 0 to 40 wt % of CaO, from 0 to 60 wt % of SrO,
from 16 to 60 wt % of MgO+CaO+SrO, from 0 to 10 wt % of Li.sub.2
O+Na.sub.2 O+K.sub.2 O+Cs.sub.2 O, from 0 to 10 wt % of PbO, from 0
to 20 wt % of ZnO, from 0 to 10 wt % of ZrO.sub.2 +TiO.sub.2, from
8 to 40 wt % of B.sub.2 O.sub.3, from 0 to 60 wt % of Ta.sub.2
O.sub.5, from 0 to 50 wt % of Nb.sub.2 O.sub.5, from 0 to 60 wt %
of Ta.sub.2 O.sub.5 +Nb.sub.2 O.sub.5, and from 0.1 to 20 wt % of
Fe.sub.2 O.sub.3 +CuO+NiO+CoO+MnO+MoO.sub.3 +WO.sub.3 +Cr.sub.2
O.sub.3 +Bi.sub.2 O.sub.3 +CeO.sub.2 +Sb.sub.2 O.sub.3 +In.sub.2
O.sub.3 +SnO.sub.2.
Inventors: |
Tanabe; Ryuichi (Yokohama,
JP), Nishihara; Yoshiyuki (Kawasaki, JP) |
Assignee: |
Asahi Glass Company Ltd.
(Tokyo, JP)
|
Family
ID: |
27527737 |
Appl.
No.: |
07/984,471 |
Filed: |
December 2, 1992 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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899156 |
Jun 15, 1992 |
5202292 |
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531750 |
Jun 1, 1990 |
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Foreign Application Priority Data
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Jun 9, 1989 [JP] |
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1-145486 |
Jul 14, 1989 [JP] |
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1-180565 |
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Current U.S.
Class: |
428/209; 428/210;
428/901; 501/66; 501/67; 501/77 |
Current CPC
Class: |
C03C
8/14 (20130101); Y10T 428/24917 (20150115); Y10T
428/24926 (20150115); Y10S 428/901 (20130101) |
Current International
Class: |
C03C
8/14 (20060101); C03C 8/00 (20060101); B05D
001/00 () |
Field of
Search: |
;428/325,689,697,699
;501/65,66,67,72,77,78 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Hacks Chemical Dictionary 1987 p. 261..
|
Primary Examiner: Group; Karl
Assistant Examiner: Gallo; Chris
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt
Parent Case Text
This is a division of application Ser. No. 07/899,156, filed on
Jun. 15, 1992, now U.S. Pat. No. 5,202,292, which is a continuation
of Ser. No. 07/531,750, filed on Jun. 1, 1990, now abandoned.
Claims
What is claimed is:
1. A ceramic substrate having a circuit pattern formed thereon,
wherein the circuit pattern is formed by firing in a non-oxidizing
atmosphere, a conductive paste and a resistor paste comprising an
inorganic component which consists essentially of
from 20 to 70 wt % of glass powder and from
30 to 80 wt % of a powder selected from the group consisting of
SnO.sub.2 powder, Sb-doped SnO.sub.2 powder and a mixture
thereof,
wherein said glass powder consists essentially of
from 12 to 50 wt % of SiO.sub.2,
from 0 to 20 wt % of Al.sub.2 O.sub.3,
from 0 to 40 wt % of MgO,
from 0 to 40 wt % of CaO,
from 0 to 60 wt % of SrO,
from 16 to 60 wt % of MgO+CaO+SrO,
from 0 to 10 wt % of Li.sub.2 O+Na.sub.2 O+K.sub.2 O+Cs.sub.2
O,
from 0 to 10 wt % of PbO,
from 0 to 20 wt % of ZnO,
from 0 to 10 wt % of ZrO.sub.2 +TiO.sub.2,
from 8 to 40 wt % of B.sub.2 O.sub.3,
either from 0.5 to 60 wt % of Ta.sub.2 O.sub.5, or
from 0.5 to 50 wt % of Nb.sub.2 O.sub.5, or
from 0.2 to 60 wt % of Ta.sub.2 O.sub.5 +Nb.sub.2 O.sub.5, and
from 0.1 to 20 wt % of Sb.sub.2 O.sub.3.
2. The ceramic substrate according to claim 1, wherein the glass
powder consists essentially of
from 12 to 50 wt % of SiO.sub.2,
from 0 to 20 wt % of Al.sub.2 O.sub.3,
from 0 to 40 wt % of MgO,
from 0 to 40 wt % of CaO,
from 0 to 60 wt % of SrO,
from 16 to 60 wt % of MgO+CaO+SrO,
from 0 to 10 wt % of Li.sub.2 O+Na.sub.2 O+Cs.sub.2 O,
from 0 to 10 wt % of PbO,
from 0 to 20 wt % of ZnO,
from 0 to 10 wt % of ZrO.sub.2 +TiO.sub.2,
from 8 to 40 wt % of B.sub.2 O.sub.3,
either from 0.5 to 50 wt % of Ta.sub.2 O.sub.5, or
from 0.5 to 45 wt % of Nb.sub.2 O.sub.5, or
from 0.5 to 50 wt % of Ta.sub.2 O.sub.5 +Nb.sub.2 O.sub.5, and
from 1 to 15 wt % of MnO and Sb.sub.2 O.sub.3.
3. The ceramic substrate according to claim 1, wherein the
substrate is made of glass ceramics.
4. The ceramic substrate according to claim 1, wherein the
substrate is made of alumina.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resistor paste composition and a
ceramic substrate. More particularly, it relates to a resistor
paste comprising SiO.sub.2 -B.sub.2 O.sub.3 system glass containing
metal oxides, and SnO.sub.2 and/or Sb-doped SnO.sub.2, which is
useful for a ceramic substrate, whereby even when fired in a
non-oxidizing atmosphere, it will not be reduced, and provides
adequate stability of e.g. resistivity.
2. Discussion of Background
Heretofore, the resistor in a hybrid integrated circuit has been
formed in such a manner that a silver (Ag) or Ag-palladium (Pd)
conductor is formed on or in a ceramic substrate, and a resistor
paste is printed between the conductor patterns, followed by firing
in an oxidizing atmosphere such as air at a temperature of from
about 850.degree. to 900.degree. C. The resistor paste used in such
a case used to be composed mainly of RuO.sub.2 and glass. However,
recently, it has been common to employ a copper (Cu) conductor
instead of the Ag or Ag-Pd conductor, from the viewpoint of the
reliability in e.g. migration.
However, the Cu conductor is oxidized unless it is fired in a
non-oxidizing atmosphere such as nitrogen. In a non-oxidizing
atmosphere, RuO.sub.2 can not be used, since it will be reduced and
will not form a resistor in such a non-oxidizing atmosphere.
Therefore, it has recently been proposed to employ a combination of
antimony (Sb)-doped tin oxide and glass powder (Japanese Unexamined
Patent Publication No. 119902/1987). However, such a combination
still has a drawback that the resistivity and the temperature
coefficient of resistivity (TCR) are not yet adequately stable.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a novel
resistor paste and ceramic substrate, which can be fired in a
non-oxidizing atmosphere such as nitrogen and which are able to
provide a constant resistivity and temperature coefficient of
resistivity (TCR).
The present invention has been made to solve the above-mentioned
problems and provides a resistor paste comprising an inorganic
component which consists essentially of from 20 to 70 wt % of glass
powder and from 30 to 80 wt % of a powder selected from the group
consisting of SnO.sub.2 power, Sb-doped SnO.sub.2 powder and a
mixture thereof, wherein the glass powder consists essentially of
from 12 to 50 wt % of SiO.sub.2, from 0 to 20 wt % of Al.sub.2
O.sub.3, from 0 to 40 wt % of MgO, from 0 to 40 wt % of CaO, from 0
to 60 wt % of SrO, from 16 to 60 wt % of MgO+CaO +SrO, from 0 to 10
wt % of Li.sub.2 O+Na.sub.2 O+K.sub.2 O+Cs.sub.2 O, from 0 to 10 wt
% of PbO, from 0 to 20 wt % of ZnO, from 0 to 10 wt % of ZrO.sub.2
+TiO.sub.2, from 8 to 40 wt % of B.sub.2 O.sub.3, from 0 to 60 wt %
of Ta.sub.2 O.sub.5, from 0 to 50 wt % of Nb.sub.2 O.sub.5, from 0
to 60 wt % of Ta.sub.2 O.sub.5 +Nb.sub.2 O.sub.5, and from 0.1 to
20 wt % of Fe.sub.2 O.sub.3 +CuO+NiO+CoO+MnO+MoO.sub.3 +WO.sub.3
+Cr.sub.2 O.sub.3 +Bi.sub.2 O.sub.3 +CeO.sub.2 +Sb.sub.2 O.sub.3
+In.sub.2 O.sub.3 +SnO.sub.2.
The present invention also provides a ceramic substrate having such
a resistor paste fired thereon.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph showing the required range and the preferred
range of the amount of Ta.sub.2 O.sub.5 relative to the resistivity
in the case where Ta.sub.2 O.sub.5 is used alone (Nb.sub.2 O.sub.5
<0.1 wt %).
FIG. 2 is a graph showing the required range and the preferred
range of the amount of Nb.sub.2 O.sub.5 relative to the resistivity
in the case where Nb.sub.2 O.sub.5 is used alone (Ta.sub.2 O.sub.5
0.1 wt %).
FIG. 3 is a graph showing the required range and the preferred
range of the amount of Ta.sub.2 O.sub.5 +Nb.sub.2 O.sub.5 relative
to the resistivity.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Now, the present invention will be described in detail.
The resistor paste of the present invention is suitable for use for
a single layer or multi-layer ceramic substrate, and is useful in
such a manner that it is formed by a method of e.g. printing, on a
ceramic substrate such as a fired and solidified alumina substrate,
or on a green sheet for a ceramic substrate, followed by firing in
a non-oxidizing atmosphere such as a nitrogen atmosphere. In this
specification, "%" means "wt %" unless otherwise specified.
In the resistor paste of the present invention, the inorganic
component consists essentially of from 20 to 70% of glass powder
and from 30 to 80% of a powder of conductive material. These
materials will be described below.
The glass powder is preferably a sinterable SiO.sub.2 -B.sub.2
O.sub.3 system glass which has adequate fluidity at a low
temperature (e.g. at a temperature of not higher than 900.degree.
C.) and which is capable of covering and sufficiently wetting the
above powder of conductive material at the time of firing.
If the content of such glass powder is less than 20%, the powder of
conductive material can not adequately be wetted, whereby the
sintered layer will have void pores, and strength of the resistor
formed by firing the resistor paste of the present invention will
be low, and the stability of the resistivity will be low. On the
other hand, if it exceeds 70%, the adhesion among the powder
particles of conductive material tends to be small, whereby the
resistivity tends to be high.
The glass powder in the present invention is preferably within a
range of from 25 to 65% within the above range.
On the other hand, as the powder of conductive material,
commercially available SnO.sub.2 or SnO.sub.2 having Sb doped
usually in the form of an oxide of Sb.sub.2 O.sub.3, may be used
alone or in combination, because such material has high
conductivity i.e. low resistivity, so that the resistivity of the
resistor of the present invention which is a composite of the
conductive material and the glass, can be adjusted to a desired
level.
Sb-doped SnO.sub.2 has a low resistivity as compared with non-doped
SnO.sub.2. The resistivity increases if the doping amount increases
to excess. When the resistance according to the present invention
is not higher than 10 M.OMEGA., the doping amount is suitably
within a range of from 0 to 20%, preferably from 0.1 to 15%, more
preferably from 1 to 10%, as calculated as an oxide of Sb.sub.2
O.sub.3. When the resistance according to the present invention is
higher than 10 M.OMEGA., the doping amount may be 20% or higher as
calculated as an oxide of Sb.sub.2 O.sub.3.
With respect to the particle size of the glass powder according to
the present invention, if the particle size is too small, the above
resistivity tends to be too high, and if it is too large, it
becomes difficult to adequately wet the glass, and void pores tend
to increase in the sintered layer, such being undesirable. The
average particle size should usually be within a range of from 0.5
to 6 .mu.m, preferably from 1 to 5 .mu.m.
On the other hand, if the particle size of the powder of conductive
material according to the present invention, is too small, the
resistivity tends to be too large, and if it is too large, the
distribution on the ceramic substrate tends to be non-uniform, and
the variation in the resistivity will be large, such being
undesirable. The average particle size should usually be within a
range of from 0.01 to 5 .mu.m, preferably from 0.05 to 3 .mu.m.
In the present invention, the glass powder consists essentially
of:
______________________________________ SiO.sub.2 12-50% Al.sub.2
O.sub.3 0-20% MgO+CaO+SrO 16-60% (MgO, 0-40%, CaO 0-40%, SrO 0-60%)
Li.sub.2 O+Na.sub.2 O+K.sub.2 O+Cs.sub.2 O 0-10% PbO 0-10% ZnO
0-20% ZrO.sub.2 +TiO.sub.2 0-10% B.sub.2 O3 8-40% Ta.sub.2 O.sub.5
0-60% Nb.sub.2 O.sub.5 0-50% Ta.sub.2 O.sub.5 +Nb.sub.2 O.sub.5
0-60% Metal oxides 0.1-20%
______________________________________
These components will be described below.
In such a composition, SiO.sub.2 is a network former of the glass,
and if it is less than 12%, the softening point will be too low,
whereby the heat resistance will be low, and the glass will easily
be deformed when it is fired again, such being undesirable. On the
other hand, if SiO.sub.2 exceeds 50%, the softening point tends to
be too high, whereby the fluidity of glass tends to be poor at the
time of firing, and it tends to be incapable of covering and
wetting the powder of conductive material. Further, void pores in
the sintered layer tend to be too many, and the stability of the
resistance will be poor. It is preferably within a range of from 15
to 45%.
Al.sub.2 O.sub.3 is not essential, but when incorporated, it
contributes to the improvement of moisture resistance. If it
exceeds 20%, the softening temperature of glass will be high, and
the sinterability tends to be poor. It is preferably not higher
than 18%.
MgO+CaO+SrO improve the solubility at the time of the preparation
of the glass powder and thus have a function to adjust the thermal
expansion coefficient. If their content is less than 16%, the above
solubility will not adequately be improved, and devitrification is
likely to result during the preparation of glass. On the other
hand, if it exceeds 60%, the thermal expansion coefficient will be
large, such being undesirable. Preferably, it is within a range of
from 18 to 55%.
Further, in the above MgO+CaO+SrO, if either MgO or CaO is 40% or
higher, the thermal expansion coefficient tends to be too large.
Preferably, it is within a range of from 0 to 35%. In the above
MgO+CaO+SrO, if SrO is 60% or higher, the thermal expansion
coefficient tends to be too large. Preferably, it is within a range
of from 0 to 55%.
Li.sub.2 O+Na.sub.2 O+K.sub.2 O+Cs.sub.2 O are not essential, but
they are effective for the improvement of the solubility of glass
and also have a function to increase the resistivity. If their
content exceeds 10%, the thermal expansion coefficient tends to be
too large, the matching with the substrate will be poor, and the
possibility of cracking in a thick film after firing increases.
Preferably, it is not more than 8%.
PbO is not essential, but it is effective as a flux component for
glass and has a function to increase the resistivity. If it exceeds
10%, the resistivity tends to be unstable. Preferably, it is not
more than 5%.
ZnO is not essential, but may be incorporated up to 20% in order to
improve the solubility of glass. Preferably, it is not more than
15%.
ZrO.sub.2 +TiO.sub.2 are not essential. However, when they are
incorporated, the moisture resistance of the resistor may be
improved. It may be added up to 10%, preferably not more than
7%.
B.sub.2 O.sub.3 is used as a flux component. If it is less than 8%,
the softening point will be high, the sintering tends to be
inadequate, and void pores in the sintered layer tend to be too
many. On the other hand, if it exceeds 40%, the water resistance of
glass will be low. Preferably, it is within a range of from 10 to
38%.
Ta.sub.2 O.sub.5 and Nb.sub.2 O.sub.5 are not essential components,
but they are useful for adjusting the resistivity and the
temperature coefficient of resistivity (TCR). By the incorporation
of Ta.sub.2 O.sub.5 and Nb.sub.2 O.sub.5, it is possible to shift
the resistivity to a higher direction and to shift TCR to the
positive direction. Their amounts are determined to meet the
desired resistivity. However, if Ta.sub.2 O.sub.5 exceeds 60%, or
Nb.sub.2 O.sub.5 exceeds 50%, when manufacturing glass
vitrification tends to be difficult.
The required ranges and the preferred ranges of Ta.sub.2 O.sub.5,
Nb.sub.2 O.sub.5 and Ta.sub.2 O.sub.5 +Nb.sub.2 O.sub.5 are shown
in FIGS. 1, 2 and 3, respectively. The main points of these FIGS. 1
to 3 will be summarized as follows.
FIG. 1 is a graph showing the required range and the preferred
range of the amount of Ta.sub.2 O.sub.5 relative to the resistivity
in a case where Ta.sub.2 O.sub.5 is used alone (Nb.sub.2 O.sub.5
<0.1 wt %).
FIG. 2 is a graph showing the required range and the preferred
range of the amount of Nb.sub.2 O.sub.5 relative to the resistivity
in a case where Nb.sub.2 O.sub.5 is used alone (Ta.sub.2 O.sub.5
<0.1 wt %).
FIG. 3 is a graph showing the required range and the preferred
range of the amount of Ta.sub.2 O.sub.5 +Nb.sub.2 O.sub.5 relative
to the resistivity.
Here, the combined use means that each of Ta.sub.2 O.sub.5 and
Nb.sub.2 O.sub.5 is at least 0.1%. Namely, if one of them is less
than 0.1%, the other is regarded as a single use.
______________________________________ Respective ranges of
Ta.sub.2 O.sub.5 and Nb.sub.2 O.sub.5 for desired levels of
resistivity (Either Ta.sub.2 O.sub.5 or Nb.sub.2 O.sub.5 is used
alone) ______________________________________ Ta.sub.2 O.sub.5 (wt
%) Nb.sub.2 O.sub.5 (wt %) Nb.sub.2 O.sub.5 < 0.1 wt % Ta.sub.2
O.sub.5 < 0.1 wt % Resistivity Required Preferred Required
Preferred (.OMEGA./.quadrature.) range range range range
______________________________________ 10K 0-18 0.5-9 0-12 0.5-6
100K 0-46 0.5-30 0-34 0.5-20 1M 0-60 0.5-50 0-50 0.5-45 10M 0-60
15-50 0-50 10-45 100M 0-60 -- 0-50 --
______________________________________
______________________________________ Respective ranges of
Ta.sub.2 O.sub.5 and Nb.sub.2 O.sub.5 for desired levels of
resistivity (Ta.sub.2 O.sub.5 and Nb.sub.2 O.sub.5 are used in
combination) Resistivity Ta.sub.2 O.sub.5 + Nb.sub.2 O.sub.5 (wt %)
(.OMEGA./.quadrature.) Required range Preferred range
______________________________________ 10K 0.2-18 0.5-9 100K 0.2-46
0.5-30 1M 0.2-60 0.5-50 10M 0.2-60 10-50 100M 0.2-60 --
______________________________________
As the above metal oxides, Fe.sub.2 O.sub.3, CuO, NiO, MnO,
MoO.sub.3, WO.sub.3, Bi.sub.2 O.sub.3, CeO.sub.2, CoO, Cr.sub.2
O.sub.3, Sb.sub.2 O.sub.3, In.sub.2 O.sub.3 and SnO.sub.2, may be
used alone or in combination. These metal oxides have a function to
adjust the resistivity and the temperature coefficient of
resistivity (TCR) and to improve the laser trimming properties.
Preferred among these metal oxides are NiO, MnO and Sb.sub.2
O.sub.3. Particularly preferred is NiO. The respective functions
will be listed below.
Fe.sub.2 O.sub.3, CuO, NiO, MnO, CoO, Cr.sub.2 O.sub.3, SnO.sub.2,
Sb.sub.2 O.sub.3 and WO.sub.3 are effective to lower the
resistivity and shift TCR to the positive direction.
MoO.sub.3 is effective to lower the resistivity and shift TCR to
the negative direction.
CeO.sub.2 is effective to increase the resistivity and shift TCR to
the positive direction.
Bi.sub.2 O.sub.3 is effective to increase the resistivity and shift
TCR to the negative direction.
In.sub.2 O.sub.3 is effective to increase the resistivity and shift
TCR to the negative direction.
Further, they are effective to improve the cutting properties for
the laser trimming to adjust the resistivity.
The respective amounts in the glass composition are determined to
meet the desired resistance, temperature coefficient of resistivity
(TCR) and laser trimming properties. However, if the total amount
of the above metal oxides is less than 0.1%, no substantial effects
will be obtained. On the other hand, if it exceeds 20%, the
resistivity drift in the high temperature storage test will be
large, such being undesirable. Preferably, the total amount is
within a range of from 1 to 15%.
Among the above metal oxides, NiO, MnO and Sb.sub.2 O.sub.3 are
excellent in the effects for adjusting the resistivity and TCR and
for stabilizing the resistivity drift. Among them, NiO is most
excellent.
The preferred ranges with their resistivity being not more than 1M
are as follows:
______________________________________ SiO.sub.2 15-45% Al.sub.2
O.sub.3 0-18% MgO+CaO+SrO 18-55% (MgO, 0-35%, CaO 0-35%, SrO 0-55%)
Li.sub.2 O+Na.sub.2 O+K.sub.2 O+Cs.sub.2 O 0-8% PbO 0-5% ZnO 0-15%
ZrO.sub.2+TiO.sub.2 0-7% B.sub.2 O.sub.3 10-38% Ta.sub.2 O.sub.5
0.5-50% Nb.sub.2 O.sub.5 0.5-45% Ta.sub.2 O.sub.5 +Nb.sub.2 O.sub.5
0.5-50% Metal oxides 1-15%
______________________________________
The resistor paste composition of the present invention is a
mixture of the respective powders in the above proportions. Now, a
process for producing the resistor paste of the present invention
and a process for producing a thick film circuit using such a
resistor paste, will be described.
An organic vehicle comprising an organic binder and a solvent, is
added to the above resistor paste composition of the present
invention, and the mixture is kneaded to obtain a paste. Such an
organic binder includes ethyl cellulose, acrylic resins,
ethylene-vinyl acetate copolymer resins and poly
.alpha.-methylstyrene resins. Likewise, the solvent includes
.alpha.-terpineol, butylcarbitol acetate, butylcarbitol,
2,2,4-trimethylpentanediol-1,3-monoisobutylate, and diethylene
glycol di-n-butyl ether. Further, a surfactant may be added as a
dispersing agent.
Then, to form a conductor on a ceramic substrate such as a fired
and solidified alumina substrate or on a glass ceramic substrate, a
conductive paste such a Cu paste containing Cu as the main
component, is formed in a prescribed circuit pattern by a method
such as printing, followed by drying and then by firing at a
temperature of from 800.degree. to 1,000.degree. C. for from 5 to
30 minutes in a non-oxidizing atmosphere such as a nitrogen
atmosphere having an oxygen concentration of not higher than about
20 ppm. The preferred ranges of this firing conditions are from
880.degree. to 920.degree. C. for from 7 to 15 minutes. Then, the
resistor paste of the present invention is printed at the
predetermined portions for resistor, followed by drying and then by
firing at a temperature of from 800.degree. to 1,000.degree. C. for
from 5 to 30 minutes in the above-mentioned nitrogen atmosphere.
The preferred ranges of this firing conditions are from 880.degree.
to 920.degree. C. for from 7 to 15 minutes.
In the case of firing a multi-layer ceramic substrate all at once,
ceramic green sheets for a ceramic substrate, having the above Cu
paste and the resistor paste of the present invention already
printed, are hot-pressed and laminated, followed by firing all at
once at a temperature of from 800.degree. to 1,000.degree. C. for
from a few minutes to a few hours in a non-oxidizing atmosphere
such as the above nitrogen atmosphere, to obtain a multi-layer
substrate.
To the resistor paste of the present invention, a coloring pigment
such as a metal oxide or heat resistant inorganic pigment, may be
incorporated for coloring in an amount of from 0 to 5%.
Further, from 0 to 5% of a nitrate, arsenic oxide, a sulfate, a
fluoride or chloride may be added as a refining agent or a melting
accelerator at the time of preparing the glass.
EXAMPLES
Starting materials for the glass powder of the present invention
were mixed in the proportions as identified in Table 1, as
calculated as oxides, and the proportions of the metal oxides are
shown in Table 2. Each mixture was put into a platinum crucible
heated under stirring at a temperature of from 1,350.degree. to
1,500.degree. C. for from 2 to 3 hours. Then, the product was
pulverized in water or formed into flakes, and further pulverized
by a pulverizer to an average particle size of from 0.5 to 6 .mu.m
to obtain glass powder. Then, a powder of SnO.sub.2 and/or
SnO.sub.2 having Sb doped in an amount of 5% as calculated as an
oxide of Sb.sub.2 O.sub.3, was adjusted to have an average particle
size of from 0.01 to 5 .mu.m. Then, such glass powder and powder of
conductive material were mixed in the proportions as identified in
Table 1 to obtain a composition of the resistor paste of the
present invention.
Then, to such a resistor paste, an organic vehicle comprising ethyl
cellulose as an organic binder and .alpha.-terpineol as a solvent,
was added, and the mixture was kneaded to obtain a paste having a
viscosity of 30.times.10.sup.4 cps. Then, Cu was screen-printed as
a conductor on a solidified alumina substrate in a prescribed
circuit pattern, followed by drying and firing at 900.degree. C.
for 10 minutes in a nitrogen atmosphere having an oxygen
concentration of not higher than 20 ppm.
Then, at the prescribed portions for resistance, the
above-mentioned resistor paste was screen-printed by a 200 mesh
screen, followed by drying and firing at 900.degree. C. for 10
minutes in a nitrogen atmosphere having an oxygen concentration of
not more than 20 ppm. The film thickness after the firing was about
15 .mu.m.
Thus, a circuit was formed on the ceramic substrate. With respect
to this circuit, the resistivity, the temperature coefficient of
resistivity (TCR) and the resistivity drift after storage at a high
temperature, were measured. The results are shown in Table 1. It is
evident from Table 1 that the resistor pastes of the present
invention are excellent in the resistance characteristics and have
adequate properties to be used as resistor pastes for forming thick
film circuits.
As Comparative Examples, similar evaluations were conducted with
respect to those other than the resistor pastes of the present
invention. These are shown in Table 3.
The respective properties were measured by the following
methods.
1) Resistivity and temperature coefficient of resistivity (TCR)
The resistivity values (R.sub.25, R.sub.-55 and R.sub.125) at
25.degree. C., -55.degree. C. and +125.degree. C. were measured by
an ohmmeter in a constant temperature tank, and the temperature
coefficients of resistivity were calculated by the following
formulas: ##EQU1##
2) Resistivity drift after storage at a high temperature
The test sample was left to stand in a constant temperature tank of
150.degree. C. for 100 hours, and the resistivity drift was
calculated by the following formula: ##EQU2##
In the above formula, R.sub.100h =the resistivity after 100 hours,
and R.sub.0 =the initial resistivity.
TABLE 1
__________________________________________________________________________
Examples Sample No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
__________________________________________________________________________
Glass compo- sition (%) SiO.sub.2 20 30 45 30 20 25 15 14 12 35 50
30 22 23 12 Al.sub.2 O.sub.3 10 0 0 10 5 0 18 0 1 14 3 0 16 8 7 MgO
5 0 10 10 0 0 15 10 0.5 1 25 2 32 0 0 CaO 20 10 10 15 10 2 5 0 0.5
2 3 15 0 40 0 SrO 14 20 0 5 30 15 30 6 58 14 0 30 0 0 58 Li.sub.2 O
0 0 2 0 0 0 0 0 0.5 5 6 0 1 0 1 Na.sub.2 O 0 2 5 0 0 0 0 0 0.5 1 0
0 0 2 2 K.sub.2 O 0 1 2 0 0 0 0 0 0.5 3 0 0 0 0 5 Cs.sub.2 O 0 0 1
0 0 0 0 0 0.5 0 0 0 0 0 1 PbO 0 3 0 0 0 0 0 0 0.5 0 0 0 2 1 0 ZnO 5
0 0 15 0 0 0 0 1 0 0 0 1 2 3 ZrO.sub.2 0 1 0 0 0 3 0 1 0.5 0 0 0 2
1 1 TiO.sub.2 0 0 0 0 0 0 0 1 0.5 0 0 0 1 2 1 B.sub.2 O.sub.3 25
21.5 18 9.5 30 35 11.5 8 8 9 10 16 8 8 8 Ta.sub.2 O.sub.5 0 0 0 0
0.5 0 0 50 0.8 0.5 1.5 2 0 1 0.5 Nb.sub.2 O.sub.5 0 10 0 0 0.5 0 0
0 14.5 0.5 1 0 0 1 0 Metal oxides Presented in Table 2 Constitution
Glass powder 40 50 55 40 25 48 70 45 38 45 47 38 45 52 35
Conductive material SnO.sub.2 60 50 0 60 75 52 20 55 62 0 53 62 55
48 65 Sb-doped 0 0 45 0 0 0 10 0 0 55 0 0 0 0 0 SnO.sub.2 Average
particle size (.mu.m) Glass powder 2.0 3.0 1.0 2.0 5.0 0.6 1.0 1.5
2.2 6.0 3.0 2.6 3.2 3.0 2.7 Powder of 1.0 0.1 1.0 0.05 0.5 5.0 0.1
0.2 0.5 1.2 0.8 0.2 1.0 0.5 1.0 conductive material Properties
Resistivity 16K 7M 1.5M 15K 7K 50K 12M 20M 115K 150K 480K 3K 120K
620K 30K (.OMEGA./.quadrature.) Hot TCR +70 +150 +30 -50 +100 +150
-120 +70 +100 +180 -130 -50 -80 -120 -250 (ppm/.degree.C.) Cold TCR
+80 +120 +80 -70 +50 +160 -100 +80 +120 +150 -160 -30 -100 -150
-230 (ppm/.degree.C.) Resistivity +0.2 -0.8 +0.5 +0.2 +0.5 +0.2
-0.05 +0.8 -0.7 +1.0 +0.8 +0.2 -0.8 -0.7 +1.0 drift (%)
__________________________________________________________________________
Examples Sample No. 16 17 18 19 20 21 22 23 24 25 26 27 28 29
__________________________________________________________________________
Glass compo- sition (%) SiO.sub.2 15 15 20 17 12 15 17 17 20 12 15
12 15 12.5 Al.sub.2 O.sub.3 12 10 10 0 20 18 13 3 5 1.5 3 0 8 0.5
MgO 0 20 5 0 20 2 0 0 6 10 8 12 5 0 CaO 0 2 1 10 0 30 0 0 6 10 2 4
5 0 SrO 45 5 12 20 0 0 40 50 6 10 10 0 8 16 Li.sub.2 O 0 0 10 0 8 0
0 0 1 2 0 0 0 0 Na.sub.2 O 0 0 0 0 0 0 0 0 1 3 2 0 0.5 0 K.sub.2 O
1 0 0 10 0 0 0 0 1 1 1 0 0.5 0 Cs.sub.2 O 0 10 0 0 0 0 0 0 1 0 2 0
0 0 PbO 0 5 10 8 0 0 2 5 2 0 2 0 0 0 ZnO 2 0 0 10 2 0 0 5 20 5 5 1
1 0 ZrO.sub.2 1 5 2 4 8 10 0 0 2 0 1.5 0 0 0 TiO.sub.2 0 5 1 2 0 0
0 10 3 0 2.5 0 0 0 B.sub.2 O.sub.3 9 10 10 11 10 10 8 9.5 8 40 12 8
8 8 Ta.sub.2 O.sub.5 0 3 1 0 0 3 0 0 1 3 15 55 0 18 Nb.sub.2
O.sub.5 0 0 1.5 0 1 2 0 0 0 2 1 0 30 35 Metal oxides Presented in
Table 2 Constitution Glass powder 32 50 40 45 41 40 37 47 35 45 40
50 46 50 Conductive material SnO.sub.2 68 50 60 55 59 60 63 53 0 55
60 50 54 50 Sb-doped 0 0 0 0 0 0 0 0 65 0 0 0 0 0 SnO.sub.2 Average
particle size (.mu.m) Glass powder 4.0 3.5 2.5 1.5 3.0 2.6 3.2 3.5
3.0 2.5 2.7 4.0 1.0 0.5 Powder of 0.5 0.8 1.5 2.0 1.0 0.1 0.8 0.01
0.1 1.0 2.5 1.4 1.5 5.0 conductive material Properties Resistivity
18K 600K 15K 320K 20K 25K 85K 550K 2.5K 960K 200K 35M 15M 85M
(.OMEGA./.quadrature.) Hot TCR -80 -20 +180 -100 +80 +90 -150 -200
-100 -250 -180 -220 -150 -250 (ppm/.degree.C.) Cold TCR -70 -40
+160 -80 +70 +100 -180 -220 -120 -200 -170 -200 -180 -220
(ppm/.degree.C.) Resistivity +0.6 -0.5 -0.8 +0.7 +1.0 +0.6 +0.8
-0.8 +1.0 +1.0 +0.6 +0.8 +0.8 -0.7 drift (%)
__________________________________________________________________________
Examples Sample No. 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44
__________________________________________________________________________
Glass compo- sition (%) SiO.sub.2 30 20 50 32 30 20 30 23 20 20 23
21 22 28 30 Al.sub.2 O.sub.3 0 0 0 0 0 8 0 0 0 0 0 0 0 5 0 MgO 5 1
0 7 5 6 5 3 6 6 6 3 5 0 5 CaO 10 5 8 10 10 2 12 7 7 5 6 7 8 20 0
SrO 10 10 12 10 28 25 8 19 30 35 27 20 22 12 30 Li.sub.2 O
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Na.sub.2 O 0 0 2 0 0 0 0 0 0 0 0 0 0
0 0 K.sub.2 O 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 Cs.sub.2 O 0 0 5 0 0 0
0 0 0 0 0 0 0 0 0 PbO 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 ZnO 0 0 1 0 0 0
0 0 0 0 0 0 0 5 0 ZrO.sub.2 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 TiO.sub.2
0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 B.sub.2 O.sub.3 25 18 14 21 25 19 25
15.6 18 15 10 10 10 11 30 Ta.sub.2 O.sub.5 0 0.5 0 0 0 15 0 30.7 0
0 22 35 28 0 0 Nb.sub.2 O.sub.5 0 45 0 0 0 0 0 0 0 0 0 0 0 0 0
Metal oxides Presented in Table 2 Constitution Glass powder 48 36
40 60 50 45 43 60 40 20 38 47 40 45 28 Conductive material
SnO.sub.2 52 64 60 40 50 55 57 40 0 80 62 53 60 55 72 Sb-doped 0 0
0 0 0 0 0 0 60 0 0 0 0 0 0 SnO.sub.2 Average particle size (.mu.m)
Glass powder 2.5 3.5 2.2 0.5 2.7 3.3 2.5 3.0 3.2 2.5 2.7 3.0 4.0
4.0 2.5 Powder of 0.5 1.0 0.3 1.0 0.5 0.8 0.05 1.0 1.5 0.8 1.0 0.5
0.8 1.0 0.5 conductive material Properties Resistivity 520K 2M 200K
35M 950K 3M 180K 75M 18K 6K 500K 15M 1.6M 350K 8K
(.OMEGA./.quadrature.) Hot TCR -140 -300 -200 -150 -180 +80 +220
-80 -70 +150 +40 -80 -60 +150 +180 (ppm/.degree.C.) Cold TCR -120
-330 -180 -140 -160 +120 +200 -60 -80 +130 +50 -50 -40 +170 +150
(ppm/.degree.C.) Resistivity +1.0 +0.7 +0.8 +1.0 +0.3 -0.5 -1.0
+0.5 +0.1 +0.2 -0.3 +0.4 -0.3 +0.2 +0.3 drift (%)
__________________________________________________________________________
TABLE 2
__________________________________________________________________________
Examples Sample No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
20 21 22
__________________________________________________________________________
Metal Oxides (wt %) NiO 1 0 5 0 0 20 0 8 0.2 15 0 0 0 0 0 0 0 0 0 0
0 0 Fe.sub.2 O.sub.3 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0.5 15 0 0 0 0 0 0
CuO 0 0.5 1.5 0 0 0 0 0 0 0 0 0 0 0 0 0 10 16.5 0 0 0 0 MnO 0 0 0.5
0 3 0 0 2 0 0 0 0 0 0 0 0 0 0 8 19 0 0 MoO.sub.3 0 0 0 0 1 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 10 20 WO.sub.3 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 Bi.sub.2 O.sub.3 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 CeO.sub.2 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 CoO 0
0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Cr.sub.2 O.sub.3 0 0 0 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Sb.sub.2 O.sub.3 0 0 0 0 0 0 0
0 0 0 0.5 5 15 11 0 0 0 0 0 0 0 0 In.sub.2 O.sub.3 0 0 0 0 0 0 0.5
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 SnO.sub.2 0 0 0 0.5 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
__________________________________________________________________________
Examples Sample No. 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38
39 40 41 42 43 44
__________________________________________________________________________
Metal Oxides (wt %) NiO 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.1 5 10 6 4 5
0 0 Fe.sub.2 O.sub.3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.5 1 0.5 0 0 0 0
0 CuO 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.1 1 0.5 0 0 0 0 0 MnO 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0.1 1 3 0 0 0 0 0 MoO.sub.3 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0.1 1 0.5 0 0 0 0 0 WO.sub.3 0.5 0 0 0 0 0 0 0 0 0 0 0 0 0.1
1 0.5 0 0 0 15 0 Bi.sub.2 O.sub.3 0 17 0 0 0 0 0 0 0 0 0 0 0 0 0.1
1 0.5 0 0 0 0 2 CeO.sub.2 0 0 0.5 18 0 0 0 0 0 0 0 0 0 0 0.1 1 0.5
0 0 0 0 0 CoO 0 0 0 0 8 19 0 0 0 0 0 0 0 0 0.1 1 0.5 0 0 0 0 0
Cr.sub.2 O.sub.3 0 0 0 0 0 0 10 20 0 0 0 0 0 0 0.1 1 0.5 0 0 0 0 0
Sb.sub.2 O.sub.3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.1 3 2 0 0 0 0 0
In.sub.2 O.sub.3 0 0 0 0 0 0 0 0 0.5 5 20 0 0 0 0.1 1 0 0 0 0 0 0
SnO.sub.2 0 0 0 0 0 0 0 0 0 0 0 2 5 20 0.1 1 0 0 0 0 0 0
__________________________________________________________________________
TABLE 3 ______________________________________ Examples Sample No.
1 2 3 ______________________________________ Glass composition (%)
SiO.sub.2 30 20 30 Al.sub.2 O.sub.3 10 15 0 MgO 0 5 5 CaO 15 25 15
SrO 20 10 15 Li.sub.2 O 0 0 0 Na.sub.2 O 0 2 2 K.sub.2 O 0 5 0
Cs.sub.2 O 0 0 0 PbO 0 0 5 ZnO 5 0 0 ZrO.sub.2 0 2 0 TiO.sub.2 0 1
0 B.sub.2 O.sub.3 20 15 28 Ta.sub.2 O.sub.5 0 0 0 Nb.sub.2 O.sub.5
0 0 0 Metal oxides 0 0 0 Constitution Glass powder 10 40 50
Conductive material SnO.sub.2 90 60 50 Sb-doped SnO.sub.2 0 0 0
Average particle size (.mu.M) Glass powder 3.0 2.0 1.0 Powder of
conductive 1.0 1.0 0.5 material Properties Resistivity
(.OMEGA./.quadrature.) 3K 30K 700K Hot TCR (ppm/.degree.C.) -2000
-1200 -800 Cold TCR (ppm/.degree.C.) -2200 -1250 -900 Resistivity
drift (%) +150 -2.0 +5.0 ______________________________________
The resistor paste of the present invention can be fired in a
non-oxidizing atmosphere such as a nitrogen atmosphere and is
capable of forming a highly reliable stabilized resistor on a
ceramic substrate, and it is particularly excellent in the
resistivity drift properties after storage at a high
temperature.
* * * * *